The present invention relates to a built-in control device for controlling a device on a vehicle, and in particularly to a failure diagnosis for a multi-core CPU (Central Processing Unit) system having a plurality of CPUs.
For the purpose of improving reliability and processing speed of the control device, in many instances recently the CPU in a control computer has been provided with a plurality of processors, and a multi-core CPU configured by a plurality of CPUs. In the above-mentioned computer, when a processor or core has failed, it is necessary to detect immediately its failure, halt the processor or core, and apply a process to prevent an adverse affect on the control.
For example, in a known redundant system disclosed in JP-A-3-15946, data output from a plurality of redundancy subsystems are compared with each other to then select an output, the data of which are consistent, from the highest reliable subsystem. JP-A-9-16535 also discloses a system in which plural outputs are compared with each other in a decision by majority to determine a conclusive output.
JP-A-3-196232 discloses a method of diagnosing a plurality of CPU cores while executing a normal computation process, without using a special diagnostic program and data. JP-A-6-332874 discloses a system for starting to execute a test program on respective processors to detect a hardware failure.